The invention relates to a two-way ball valve for liquid and/or gaseous flowing media, with a valve fitting consisting of two interconnected housing parts and in which a ball with a bore for the media throughflow and with a drive shaft running perpendicularly with respect to the bore is mounted rotatably, and in which are arranged coaxially with respect to the longitudinal axis of the valve fitting, on both sides of the ball, sealing half shells which butt one against the other and which surround the ball and completely fill the dead space between the valve fitting and the ball, the sealing half shells having in the axial direction in each case an end-face orifice corresponding at least to the cross section of the bore of the ball, and having, on the annular surfaces butting one against the other, in each case a semicircular radial orifice for the drive shaft.
In industry and for the infrastructure of residential areas, media are transported in pipelines which are exposed to changing pressures and temperatures. To regulate the throughflow quantities, regulating members, in particular also ball valves, are used in the pipelines, in order to ensure optimal operating conditions and environmental protection.
DE 7703253 U1 already discloses a ball valve capable of being used as a shut-off and regulating member for liquid and gaseous flowing media and having as a closing piece a rotatable and bored-through ball arranged in a housing. The bore in the ball, as a function of its relative rotary position in the housing, can selectively be aligned with the inlet or the outlet orifice of the housing, or be set out of alignment with it. Further, the ball valve with a circularly delimited regulating disk is arranged fixedly with respect to the housing, directly in front of and/or behind the ball in the direction of flow, and is aligned with the inlet and/or the outlet of the housing and which has throttle orifices dimensioned correspondingly to the desired regulating characteristic.
It is known from U.S. Pat. No. 4,815,704 to use in a ball valve sealing rings or sealing shells which reduce the dead space in the form of an annular gap between the ball and valve fitting. This dead space is relatively large because the two sealing half shells are arranged at a considerable distance from one another. The backwash with the flowing media, although being reduced somewhat, is not prevented. Dead spaces in fittings of ball valves, in which part of the flowing medium may be trapped, always entail the risk that deposits of medium creep between the ball and valve housing, decay in the dead volume and contaminate the medium flowing through. Since the customary dead volumes are appreciable, this constitutes a potential risk which cannot be ignored.
According to DE 7918227 U1, a ball with a housing having a through bore and with a rotatable shut-off ball is configured in such a way that it is possible for the shut-off ball to be mounted so as to be completely free of any dead space. This dead space is filled in each case by a shell-like sealing ring consisting of sealing material. The sealing rings butt on the circumference one against the other on the end face.